/Engine/Source/Developer/Localization/Public/PortableObjectFormatDOM.h
Sets the language.
Returns true if the function was able to successfully set the language code and pair it with a known culture, false otherwise.
bool SetLanguage ( const [FString](API\Runtime\Core\Containers\FString) & LanguageCode, const [FString](API\Runtime\Core\Containers\FString) & LangPluralForms )